1. Field of the Invention
The invention relates to valves and, more particularly, relates to a valve that is openable by a float and that remains open against closing forces generated by fluid flow through the valve. The invention additionally relates to a brine valve having these characteristics, a water softener incorporating a brine valve having these characteristics, and/or a method of operating a valve having these characteristics.
2. Discussion of the Related Art
Float-responsive valves are used in a variety of applications in which a float-responsive valve actuator holds a valve element of the valve in its open position against closing forces imposed on the valve element by fluid flowing through the valve. One example, but by no means the only possible example, is a so-called “brine valve” of a water softener. Water softeners are widely used for removing calcium and other deposit-causing materials from so-called “hard water.” The typical water softener relies on an ion exchange process taking place in an ion-exchange resin bed stored in a resin tank of the water softener. As the water to be processed passes through the resin-filled tank, ions of calcium and other minerals in the water are exchanged with ions found in the resin, e.g., sodium or potassium, thereby removing objectionable ions from the water and exchanging them for less objectionable ions from the resin.
The capacity of the resin to exchange ions or otherwise treat the water is finite and is reduced during the ion exchange process. If measures are not taken to regenerate the resin by replacing the undesirable ions with desirable ions, the ion exchange capacity of the resin will become exhausted. Water softeners are typically configured to periodically regenerate the ion exchange resin stored in the resin tank. Regeneration typically involves chemically replacing the objectionable ions such as calcium ions from the resin with less objectionable ions such as sodium ions. This replacement is typically performed by introducing a regenerant solution of sodium chloride or potassium chloride into the resin bed from a brine tank and thereafter flushing the spent regenerant solution from the bed. The solution is formed during a “fill” phase of the regeneration cycle by directing fresh water into the brine tank from a control valve on the resin tank, where the water contacts and dissolves the salt or the like from a regenerating agent in the tank to form the solution. Regneration of the ion exchange resin takes place during and following a “draw” phase of the regeneration cycle when the solution is transferred from the brine tank, through the control valve, and into the resin tank.
Fluid flow between the control valve and the brine tank of a typical water softener is controlled by a brine valve located in the brine tank and capable of selectively shutting off a flow passage through which fluid flows to and from the brine tank. The brine valve typically is located at the top of a vertical tube or “riser” in the brine tank and is coupled to a float that rises and falls with liquid levels in the brine tank. The typical brine valve includes a poppet, flapper or other valve element that selectively (1) seals against a seat to prevent flow through the valve and (2) moves away from the seat to permit flow through the valve. The valve element can be opened either by downward movement of the float or by suction forces within the riser. For example, during the draw phase of the regeneration cycle, liquid is drawn upwardly through the riser under suction force to force the valve element open and draw liquid from the bottom of the brine tank, through the valve, and to the resin tank. Conversely, during the fill phase, a valve actuator holds the valve element in its open position, and fluid flows downwardly through the valve to fill the brine tank to the desired level. If the liquid rises to sufficient height to lift the float to its raised position, the float moves the valve actuator to a position closing the valve. (In some situations, the float acts directly on a poppet without a valve actuator.) Flow-fill systems without timed refill or with relatively inaccurate timers rely on closure of the brine valve to determine the level of liquid in the brine tank. The brine valve functions as a primary shut-off valve in this type of system. A “timed brine” system relies at least in part on a timer to terminate the fill cycle. Fluid is supplied to the tank at a known flow rate, and the timer is set to shut off fluid flow simultaneously with the liquid level reaching the desired fill volume. Systems with relatively accurate timers will typically set the raised position of the float above the desired fluid level, in which case the timer is relied upon for primary shut-off and the fill phase usually terminates before the brine valve closes. The float responsive brine valve functions as a “safety float” or secondary shut-off valve in this type of system. In both types of systems, a float responsive valve actuator maintains the brine valve in its open position during the fill phase. It also closes the valve element at the end of a fill phase when the brine valve serves as a shut-off.
Fluid often flows into the brine valve from above very turbulently during the fill phase. The rapidly flowing turbulent fluid, often entraining a substantial volume of air, can impose relatively strong closing forces on top of the valve element. If these forces are strong enough, they can drive the valve actuator to prematurely lift the float, thereby forcing the valve element against the seat and preventing the flow of fluid into the brine tank. As a result, the fill cycle may end without the fluid level in the brine tank achieving its desired level. This is known as a “short fill” condition, which results in a “short salt” condition in the subsequent draw phase because insufficient solution is present in the tank to provide full ion exchange with the resin in the resin tank. Water softener performance therefore degrades.
The above problem can be avoided, at least to a large extent, by oversizing the float so it is exceedingly heavy and, therefore, is relatively insensitive to forces imposed on it by the valve actuator through the transmission of closing forces through the flapper. However, the heavier float still may be susceptible to premature brine valve closure during periods of unusually high velocity or unusually turbulent fluid flow through the brine valve during the fill phase.
The “short fill” problem can also be reduced by placing a diverter structure such as a baffle or cage above the valve element to reduce the impact forces imposed on the valve element by the incoming fluid stream. However, such diverters are only partially effective and may hinder valve operation during the draw phase of the regeneration cycle.
The need has additionally arisen to provide a float-responsive brine valve that is usable, e.g., in a water softener and that is relatively immune to closing forces imposed on the valve element of the valve by fluid flowing through it.